Generally, an insert is fastened to a cutting tool mounted on a machine tool and is used for cutting a workpiece made of iron, non-ferrous metal, non-metal material, and so on.
Such an insert typically has an upper surface, a lower surface, and a plurality of side surfaces connecting the upper surface and the lower surface. An upper cutting edge is provided between the side surface and the upper surface, and a lower cutting edge is provided between the side surface and the lower surface.
FIG. 8 is a plan view of a conventional milling insert, FIG. 9 is a side view of the milling insert of FIG. 8, and FIG. 10 is a view of a milling tool equipped with the milling insert of FIG. 8.
As shown in FIGS. 8 and 9, an example of the conventional milling insert 10 can be found in Korean Patent No. 10-1240880, which includes an upper side (upper surface) 11, a lower side (lower surface) 12 and a plurality of blade surfaces (side surfaces) 13A, 13B, 14A, 14B, 15A and 15B formed therebetween, in which the upper side 11 and the lower side 12 are substantially the same such that both sides can be used, and in which a main cutting blade (main cutting edge) 16 and a sub cutting blade (sub cutting edge) 17 are formed such that the intersecting lines between the blade surface and the upper and lower sides are substantially perpendicular to each other.
In addition, the conventional milling insert 10 is mounted in the pocket of the milling tool 40, as shown in FIG. 10. Specifically, some of a plurality of blade surfaces are mounted on the seat surface of the pocket of the milling tool 40, and the other blade surfaces are positioned on the outer circumferential surface and the bottom surface of the milling tool 40. Accordingly, the main cutting blade 16 formed on the other blade surface side is placed on the outer circumferential surface of the milling tool 40, and the sub cutting blade 17 is placed on the bottom surface of the milling tool 40, thus cutting a perpendicular groove on the workpiece 50 with rotation of the milling tool 40.
However, in the conventional milling insert 10, since the main cutting blade 16 and the minor cutting blade 17, which are formed on some of the blade surfaces, are perpendicular, some of the blade surfaces mounted on the seat surface of the milling tool 40 also have a structure in which they are perpendicular to each other, and accordingly, it is difficult to effectively control the centrifugal force exerted on the milling insert 10 during rotation of the milling tool 40 due to the poor fastening property with the milling tool 40. That is, such deteriorating fastening property of the milling insert 10 with respect to the milling tool 40 causes a problem during rotation of the milling tool 40 that the milling insert 10 or the milling tool 40 shakes or wears, thus shortening the lifespan of the milling insert 10 or the milling tool 40.